Patent Document 1: JP-A-2007-189549
A power line communicator as described in Patent Document 1 is denoted as a PLC, and in recently, the power line communicator is used domestically. The power line communicator outputs a data modulation signal into a power line (for example, referring to Patent Document 1).
According to Patent Document 1, the power line communicator includes a wide band filter passing through a PLC signal of an entire communication frequency band, a narrow band filter passing through the PLC signal corresponding to each frequency band, a receiver for processing the PLC signal passing through the wide band filter and the narrow band filter, a modem inputting a received data from the receiver and transmitting date to the power line through a transmitter. The each of the frequency band is obtained by separating the entire communication frequency band into multiple frequency bands, and an influence, which disturbs a power line carrier communication, of noise, a disturbing signal or the like on the power line may be reduced, so that the communication may be performed properly.
The inventor of the present application has found the following.
The power line communicator in Patent Document 1 transmits a data on the power line of a business alternating current (AC) power source. The inventor has focused on a power line data transmitter that superimposes a data modulation signal on a direct current (DC) power line of a battery power line or the like, and transmits a DC power and the data through the DC power line.
A vehicle user in recent years requests to confirm a battery voltage reduction, a going off of a stop lamp, a residual quantity lowering of washer liquid, or the like in a check at a starting time. The above information has a relatively small amount of information. Thus, a communication speed may be slow, and a communication frequency may be low. It is not necessary to perform a communication process at a high speed or frequently with using a controller area network (CAN), a local interconnect network (LIN), or the like. It is preferable that a communication process suitable for this application may be realized by a circuit as simple as possible.